System for withdrawing small amounts of body fluid

1. A system, comprising:

a disposable lancing unit having a needle with a distal end for piercing a surface of skin, wherein the needle has at least one capillary structure that is open to the outside from at least the distal end to at least an upper end of the needle;

a drive unit configured to hold the distal end of the needle below the surface of the skin and the upper end above the surface of the skin during fluid collection; and

wherein the capillary structure is configured to transport body fluid solely via capillary action.

2. The system of claim 1 , in which the disposable lancing unit has a holding area.

3. The system of claim 2 , in which the holding area has a detection zone for detecting one or several analytes, the detection zone being arranged for taking up body fluid from the capillary structure.

4. The system of claim 3 , wherein the detection zone includes a reagent for detecting the analytes in the body fluid.

5. The system of claim 2 , in which the capillary structure and holding area are integrally connected together.

6. The system of claim 2 , in which the holding area and capillary structure are integrally manufactured from a single piece of material.

7. The system of claim 2 , in which the holding area and capillary structure are manufactured from a semiconductor.

8. The system of claim 1 , wherein the drive unit is configured to partially retract the lancing unit in the skin so that the capillary structure remains in part in the skin to promote pooling of body fluid.

9. The system of claim 1 , in which the length of the capillary structure is in the range from 0.3 to 3 mm and the cross-section of the capillary structure is in the range from 0.03 to 0.8 mm.

10. The system of claim 1 , wherein:

the capillary structure has an aspect ratio from 2 to 5; and

the capillary structure has a wetting angle of less than 90 °.

11. A method, comprising:

piercing a surface of skin with a lancing unit by actuating a drive unit;

collecting body fluid with an uncovered capillary groove of the lancing unit by positioning the lancing unit with the drive unit so that the uncovered capillary groove extends from below the surface of the skin to above the surface of the skin; and

transporting the body fluid in the uncovered capillary groove solely via capillary action to a detection zone of the lancing unit.

12. The method of claim 11 , further comprising:

said collecting the body fluid includes allowing the capillary groove to reside within the skin for a collection period.

13. The method of claim 11 , further comprising:

retracting partially the lancing unit in the incision so that the capillary groove remains in part in the skin to promote pooling of the body fluid.

14. The method of claim 11 , wherein the lancing unit remains at a maximum penetration depth into the skin during said collecting.

15. The method of claim 11 , wherein the body fluid is drawn from both the surface of the skin and below the surface of the skin during said collecting.

16. The method of claim 11 , further comprising:

detecting analyte in the body fluid in the detection zone.

17. A method of manufacturing a disposable lancing unit, comprising:

creating an open capillary groove in a surface of a holding area from a distal end of a lancing tip to a holding area, the capillary groove being configured to draw body fluid solely via capillary action;

leaving the open capillary groove uncovered along the entire length of the lancing tip; and

applying a detection zone over the capillary groove at the holding area.

18. The method of claim 17 , further comprising applying a window over the detection zone.

19. The method of claim 17 , wherein said applying includes applying a reagent over the holding area.